1. Field of the Invention
In most jurisdictions, sewage treatment authorities require that the septic effluent flowing from a leaching field flow a predetermined minimum distance through a porous medium, such as natural soil, to assure that the septic effluent is thoroughly treated and is completely dispersed. In most cases the minimum distance is four feet. Some jurisdictions require only 2 feet others as much as 6 feet. The purpose of the separation is to assure that the effluent flowing down from the leaching field is fully treated.
The invention is particularly suited to terrain where the water table is at or higher than the prescribed minimum dispersion distance discussed above. The invention also enables the use of leaching fields in soils, such as clay or above the ground where the ground cannot pass percolation tests, such as ledge or a particular thick layer of clay.
2. Definitions
For purposes of this discussion the term xe2x80x9cvadose zonexe2x80x9d shall apply to the aerobic region outside of the conventional leaching field through which the septic effluent from the leaching field flows and receives additional treatment and is dispersed to the surrounding soil and eventually into the water table.
Typically a leaching field is constructed in sand. Soil or dirt is hereby defined to mean the compacted natural material surrounding the leaching field. The soil or dirt is less porous than sand.
3. Related Prior Art
U.S. Pat. No. 4,192,628 to German issued Mar. 11, 1980 is directed to a distributor unit for use in leaching fields. It comprises a hollow open-bottomed concrete structure with a central cavity filled with sand. Effluent from a septic tank to the sand bed and generally out the bottom. The side walls have openings to allow evaporation of liquid from the central cavity.
U.S. Pat. No. 5,547,589 to Carol II issued Aug. 20, 1996 is directed to a Water recovery from a septic tank. A modular vertical filter extends into the ground. Water accumulates at the bottom of the filter and is pumped into the surrounding soil.
U. S. Pat. No. 5,934,451 to Presby issued Sep. 21,1999 is directed to using multilayer of fabric to process septic effluent. Each layer being of a selected denier. The fabric is used in combination with conduit in a drainage field or leaching field.
4. Objects of the Invention
The principal object of the invention is to provide a means for using conventional leaching fields in soil with unsuitable drainage or in terrain where the separation between a proposed leaching field and its water table does not meet specifications i.e., the water table is too high for normal use with a conventional leaching field.
It is also an object of the invention to construct a vadose zone that will direct the septic effluent from a leaching field to disperse though soil for a predetermined distance prescribed by regulations.
It is another object of the invention to construct a vadose zone situated to the side of, the leaching field.
It is another object of the invention to construct a vadose zone in which septic effluent is forced to flow laterally by an impervious barrier constructed under an otherwise conventional leaching field.
In accordance with the invention there is constructed a conventional leaching field such as a number of perforated pipes embedded within sand or other porous media. A impervious barrier is placed under the leaching field to prevent the effluent from percolating vertically down into the soil. The impervious barrier extends laterally in all directions for a prescribed distance to force the effluent from the leaching field to flow sideways from the sand into soil or dirt. The barrier creates a vadose zone to the side of the leaching field starting where the sand ends and the soil begins. At the edge of the barrier the effluent is permitted to flow naturally downward through the soil or over the ground in the case of ledge.